Method of and apparatus for managing a length of optical fibre

ABSTRACT

A method and apparatus for managing a length of optical fiber by housing the length of optical fiber in a duct, the length of optical fiber being so coiled as to extend along the duct and the length of optical fiber being connected to a plurality of fiber-joining devices positioned along the duct. The fiber-joining devices are contained in modules which are removably attached to the outer periphery of the duct.

FIELD OF THE INVENTION

The invention relates to a method of and apparatus for managing a lengthof optical fibre.

BRIEF SUMMARY OF THE INVENTION

The invention provides a method of managing a length of optical fibreincluding the steps of:

-   -   housing the length of optical fibre in a duct, the length of        optical fibre being so coiled as to extend along the duct, the        coils of the optical fibre being free to expand, under the        natural tendency to straighten, restrained by the inner        periphery of the duct,    -   providing a plurality of modules removably attached to the outer        periphery of the duct at intervals along the duct,    -   locating a plurality of devices in the modules, for attachment        to the length of optical fibre at a plurality of positions        adjacent to the modules and    -   connecting the length of optical fibre to selected ones of the        devices in the modules.

Preferably, the method includes the step of

providing a length-wise slot in the duct and connecting the length ofoptical fibre through the slot to selected ones of the devices in themodules.

Preferably, the method includes the step of withdrawing selected devicesby detaching the modules containing the selected devices from the duct.

Preferably, the method includes the step of returning the selecteddevices by attaching the modules containing the selected devices to theduct.

Preferably, the method includes the step of including a plurality offibre-joining devices in the modules.

The invention also provides an apparatus for managing a length ofoptical fibre including:

-   -   a coiled length of optical fibre.    -   a duct the inner periphery of which is of a size and shape to        house the length of optical fibre so coiled as to extend along        the duct, the coils of the optical fibre being free to expand,        under the natural tendency to straighten, restrained by the        inner periphery of the duct,    -   a plurality of modules removably attached to the outer periphery        of the duct at intervals along the duct and    -   a plurality of devices in the modules, for attachment to the        length of optical fibre at a plurality of positions adjacent to        the modules,    -   the length of optical fibre, when housed in the apparatus, being        connected to selected ones of the devices.

Preferably, the apparatus includes a length-wise slot in the duct, thelength of being connected through the length-wise slot to selected onesof the devices.

Preferably, the inner periphery of the duct is of a size and is socontoured as to allow the coils of the optical fibre to expand to aradius of about the minimum fibre bend-radius required for satisfactorysignal transmission.

Preferably, the inner periphery of the duct is cylindrical.

Preferably, the devices in the modules include fibre-joining devices.

BRIEF DESCRIPTION OF THE DRAWING

A method of and apparatus for managing a length of optical fibre willnow be described by way of example only with reference to theaccompanying drawing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The apparatus includes a cylindrical duct 1 having a length-wise slotmaking the inner periphery of the cylindrical duct accessible throughthe slot. A first module 2 is removably attached to the outer peripheryof the cylindrical duct 1 and contains a first fibre-joining device 3. Asecond module 4 is removably attached to the outer periphery of thecylindrical duct 1 and contains a second fibre-joining device 5. Alength of optical fibre 6 is housed in the cylindrical duct 1 and is socoiled as to extend along the cylindrical duct 1, the coils of theoptical fibre being free to expand, under the natural tendency tostraighten, restrained by the inner periphery of the cylindrical duct 1.The first module 2 is spaced from the second module 4 along thecylindrical duct 1 by about the coiled length of the optical fibre 6which is attached, at one position, to the adjacent first fibre-joiningdevice 3 and, at another position, to the adjacent second fibre-joiningdevice 5.

The specific manner in which the first module 2 and the second module 4are removably attached to the cylindrical duct 1 is not shown in thedrawing but may include ribs on the outer periphery of the cylindricalduct 1 into which the first module 2 and the second module 4 areremovably clipped. Other means of removable attachment may also be used.

The optical cable 6 extends through the slot in the cylindrical duct 1enabling connection to the first and second fibre-joining devices 3 and5.

The maintenance of the optical fibre 6 requires that the fibre-joiningdevices 3 and 5 should be accessible for servicing and other purposes.The first fibre-joining device 3 may be removed by withdrawing the firstmodule 2, at which time a part of the length of optical fibre 6 adjacentto the first fibre-joining device 3 is readily pulled from thecylindrical duct 1 because of the coiled lay-up of the optical fibre 6.Similarly, on the return of the fibre-joining device 3, the part of thelength of the optical fibre 6 pulled from the cylindrical duct 1 isreadily replaced in the cylindrical duct 1 and returns to the coiledlay-up. A corresponding situation exists in relation to the removal andreturn of the cable-joining device 5.

There is a minimum fibre bend-radius for satisfactory operation of thelength of optical fibre 6 and the size and shape of the inner peripheryof the duct 1 are so chosen as to permit the coiled length of opticalfibre 6 to meet the restrictions on fibre bend-radius. A cylindricalinner periphery for the duct 1 is satisfactory and it will beappreciated that minor departures from truly cylindrical aresatisfactory. An inner periphery of oval transverse cross-section forthe duct 1 is also satisfactory. Also satisfactory are other transversecross-sections which permit the coiled length of optical cable to becylindrical or near-cylindrical.

The width of the slot in the duct 1 in relation to the width of the duct1 is a matter of the balance between housing the optical fibre 6effectively and the ease with which an appropriate amount of the opticalfibre 6 may be withdrawn with a fibre-joining device 3 or 5.

The slot may be omitted altogether and connection made through the openends of the duct but the absence of a slot makes the removal offibre-joining devices more complicated, although such removal is thenstill possible.

The accompanying drawing shows only modules 2 and 4 and fibre-joiningdevices 3 and 5 but it will be understood that many more modules andfibre-joining devices may be employed according to the length of theoptical fibre 6. Connection of the optical fibre 6 to devices in themodules other than fibre-joining devices is possible.

1. A method of managing a length of optical fiber, comprising the stepsof: a) housing the length of optical fiber in a duct, and coiling thelength of optical fiber into coils that extend along the duct, the coilsof the optical fiber being free to expand, under a natural tendency tostraighten, and being restrained by an inner periphery of the duct; b)providing a plurality of modules removably attached to an outerperiphery of the duct at intervals along the duct; c) locating aplurality of devices in the modules, for attachment to the length ofoptical fiber at a plurality of positions adjacent to the modules; andd) connecting the length of optical fiber to selected ones of thedevices in the modules.
 2. The method as claimed in claim 1, includingthe steps of providing a lengthwise slot in the duct, and connecting thelength of optical fiber through the slot to selected ones of the devicesin the modules.
 3. The method as claimed in claim 1, including the stepof withdrawing the selected ones of the devices by detecting the modulescontaining the selected ones of the devices from the duct.
 4. The methodas claimed in claim 3, including the step of returning the selected onesof the devices by attaching the modules containing the selected ones ofthe devices to the duct.
 5. The method as claimed in claim 1, includingthe step of including a plurality of fiber-joining devices in themodules.
 6. An apparatus for managing optical fiber, comprising: a) acoiled length of the optical fiber having coils; b) a duct having aninner periphery which is of a size and shape to house the coiled lengthof optical fiber so as to extend along the duct, the coils of theoptical fiber being free to expand, under a natural tendency tostraighten, and being restrained by the inner periphery of the duct; c)a plurality of modules removably attached to an outer periphery of theduct at intervals along the duct; d) a plurality of devices in themodules, for attachment to the length of optical fiber at a plurality ofpositions adjacent to the modules; and e) the length of optical fiberbeing connected to selected ones of the devices.
 7. The apparatus asclaimed in claim 6, including a lengthwise slot in the duct, the lengthof optical fiber being connected through the lengthwise slot to theselected ones of the devices.
 8. The apparatus as claimed in claim 6,wherein the size of the inner periphery of the duct is so contoured asto allow the coils of the optical fiber to expand to a radius of about aminimum fiber bend-radius required for satisfactory signal transmission.9. The apparatus as claimed in claim 8, wherein the inner periphery ofthe duct is cylindrical.
 10. The apparatus as claimed in claim 6,wherein the devices in the modules include fiber-joining devices.